U.S. Pat. No. 4,144,659 discloses a boot at the interior of which is disposed an inner sole whose heel is provided with a support constituted by a lug placed at the center of the heel. This arrangement makes it possible to change at will the height of the heel with respect to the plantar region of the foot, and permits a slight pivoting movement of the foot at the interior of the boot, such that the weight of the skier is brought to bear on the inner or outer edge, according to the direction he wishes to take. The result of this arrangement is an amount of play of the foot inside the ski boot which is absolutely unacceptable.
U.S. Pat. No. 2,183,197 discloses a boot for normal walking which is provided with an inner sole, solid with the boot, provided on its lower face with plates connected to screws placed in threaded holes passing through the outer sole. It is thus possible, by turning the screws, to modify the camber of the sole, raising the plantar arch. Swiss Pat. No. 506,261 discloses an analogous arrangement, more particularly adapted to ski boots, comprising two plates respectively located in the plantar and heel regions of the foot, these plates also being connected to screws traversing the inner sole. Each plate comprises a plurality of screws disposed at its periphery such that it is possible simultaneously to raise the inner sole to a greater or lesser extent, and to change its inclination by means of the peripheral screws. This arrangement has the disadvantage of rather complex operation as regards the adjustment of lateral inclination. Both the U.S. and Swiss patents utilize screws traversing the outer sole and regulated through the exterior by means of a turn-screw; this is not convenient. Moreover, the orifices may be blocked by snow, ice or soil.
U.S. Pat. No. 3,922,800 discloses a ski boot comprising an inserted inner sole, comprising four adjustable chocks arranged in pairs, one pair at the level of the heel and one pair at the level of the plantar region of the foot. These chocks have asymmetrical profiles, such that both the longitudinal and lateral inclinations can be varied. However, these chocks are carried by transverse axles actuated by turn-screws, such that their placement into operation is delicate and complex. Moreover, these mechanisms are subject to being blocked by snow, ice or corrosion.